1. Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY 14642.
2. Present address: Center for Retrovirus Research, College of Veterinary Sciences, 1900, Coffey Road, Columbus, OH 43210.
3. Max Delbrück Center for Molecular Medicine, 13092 Berlin, Germany.
4. University of Debrecen, 4032 Debrecen, Hungary.
5. Departments of Neurology, University of Rochester Medical Center, Rochester, NY 14642.
6. Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642.
7. Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642.